Bill, I signed up for the course, but couldn't find the lecture room.
I don't bother with contracts, just use a 321 SIM from Three. It suits me, I don't stream hours of video, just general internet surfing and e-mails, odd text and phone, and £20 lasts me all season! Anyway, why should the provider worry about tethering? Surely it's you who's paying to have it delivered to your phone, what's it got to do with them what you do with it?
Mostly, yes. The usual blackspot of Horning was a no-no, but elsewhere seemed OK. The South side of the Neatishead arm of Barton was dead, but move 100 yards to the North side - full signal! That's how hit and miss it can be.